The transport ministry plans to promote the installation of flight data recorders in small aircraft in light of a spate of accidents involving helicopters and planes that didn’t have the devices, ministry officials say.

The recorders play a vital role in accident investigations by providing data on altitude, speed and engine status, but small aircraft in Japan are not required by law to install them, so few pilots do. When a small aircraft has an accident, however, it is difficult to find the cause without such data.

The crash of a rescue helicopter in Gunma Prefecture earlier this month resulted in nine deaths. The Bell 412EP chopper, which belonged to the Gunma Prefectural Government, did not have a flight data recorder.

The Land, Infrastructure, Transport and Tourism Ministry is thus considering streamlining procedures to approve use of simplified, lower-priced recorders, the officials said Sunday.

Under Japanese law, airplanes with a maximum take-off weight of over 5.7 tons and helicopters rated at over 7 tons are required to have flight data recorders.

Small airplanes can be equipped with recorders but installing them costs several tens of thousands of yen, which is deemed one reason why many do not have them.

Flight data recorders can gather around 80 types of data. Simplified devices made overseas can record around 10 types of basic data, along with images and audio recordings of the cockpit.